Sea-ice decline due to more than warming alone
Sea-ice decline due to more than warming alone
复制标题
海冰减少不仅仅是变暖造成的
作者：
J. Slingo;R. Sutton
SIR——今年夏天北极海冰覆盖面积的急剧减少被广泛报道，例如在您的新闻报道“北极融化打开了西北通道”（Nature 449, 267; 2007）中，并经常将其归因于全球变暖。尽管过去四十年海冰面积的逐渐减少与全球变暖的预期相符，但今年海冰覆盖面积的减少不太可能仅仅用温度变化来解释。风型的变化对海冰的分布有重要影响。 2007 年整个夏季，北冰洋上空持续存在异常气压和风型。观测到的冰盖从西伯利亚海和波弗特海向北和向东迁移到北极盆地，与对异常风的预期反应一致。这些北极风异常是今年夏天全球范围内极不寻常的环流模式的一部分，其原因尚不清楚。东太平洋日益严重的拉尼娜现象无疑对全球产生了重大影响，过去事件的一些证据表明，拉尼娜现象使环流倾向于今年夏天出现的异常模式。
SIR—The dramatic loss of sea-ice cover over the Arctic this summer was widely reported, for example in your News story ‘Arctic melt opens Northwest passage’(Nature 449, 267; 2007), and frequently attributed to global warming. Although the gradual decline in sea-ice extent during the past four decades is in line with that expected from global warming, it is very unlikely that the loss of sea-ice cover this year is explicable solely in terms of temperature change. Changing wind patterns are an important influence on the distribution of sea ice. Throughout summer 2007, exceptional pressure and wind patterns persisted over the Arctic Ocean. The observed migration of ice cover, from the Siberian and Beaufort seas northwards and eastwards into the Arctic Basin, was in line with the expected response to the anomalous winds. These Arctic wind anomalies were part of a global-scale pattern of highly unusual circulation this summer, the causes of which are as yet unclear. The growing La Niña in the East Pacific undoubtedly had a major influence globally, and there is some evidence from past events that La Niña predisposes the circulation towards the type of exceptional patterns seen this summer.